If your Birthday Challenge involves bouldering, biking, posing and eating your age in sushi, suit up in these stretchy tights. Solids are made of nylon/spandex and heathers are made of polyester/spandex-both of which wick moisture, dry quickly and feel soft against your skin. The fabric also features incredible recovery and softness, but will remain supportive and breathable all day long. Fair Trade Certified sewing. Fabric is bluesign approved.